I'm now going to do the thing that I think you're not supposed to do which is analyze the joke (rather than just appreciate it). My wife has been working hard at writing short stories and I've been observing the learning process and reading a lot of McSweeny's. Comedy writing is a true skill (like Comedy itself) -- and I think this piece really nails it. Comedy is about the unexpected -- leading a reader down a path and then changing directions in a way that provokes laughter, not confusion.
The first brilliant line: "The second time I bit you, I think I was just hungry." The title and opening paragraph imply and lead the reader into thinking that this was a joke about a single bite (which itself is absurd). When that line hits, the absurdity is amped up.
In fact that whole paragraph escalates and escalates the absurdity: "I hadn’t had any breakfast that morning" to "Okay. Full, full disclosure: I’d had a small breakfast" to "The sad irony is that my briefcase was full of leftover sausages from breakfast."
Anyway, I won't droll on here. A great piece and worth digesting if you have any interest in comedy writing :)